Sorbent boom

ABSTRACT

A panel-shaped sorbent boom for the removal of oil and other chemicals from water.

BACKGROUND

When oil or similar hydrophobic chemicals are spilled into waterways,they typically float, forming a layer or “slick” on the surface. Theremoval of this slick is essential to prevent the fouling of beaches,riverbanks, and other areas that the oil might come into contact with,and also to permit the entry of oxygen and sunlight essential to theaquatic ecosystem. It has been well known in the art to use sorbentbooms for this purpose. Such booms are long sock-like tubes filled witha material which absorbs oil and similar hydrophobic liquids, but doesnot absorb water. These tubes are often linked end-to-end to create achain of booms intended to surround a spill (or in the case of a spillin a river or stream, span the flow). However, although this design hasbeen in use for many years, it has not proven satisfactory in practice.Such booms typically permit substantial quantities of oil to passunderneath them rather than being absorbed. Their round shape limits thesurface area which can be exposed to oil, and prevents them from beingweighted to float at an appropriate depth. Attempts to mitigate thisproblem have typically involved the placement of a hard barrier boombehind the sorbent boom so that the oil is trapped in close proximity tothe sorbent and therefore more likely to be absorbed. This solution isexpensive, because two booms are employed, requiring two deployment andrecovery efforts using redundant equipment. Hard booms are also veryheavy, and therefore difficult to transport and deploy, as well subjectto damage by wind or current. In addition, a hard boom may not bepractical for use in rapidly flowing water such as small streams.

Another approach to dealing with spills in flowing water has been theuse of “filter fences.” These are literally fences, consisting of postsand water-permeable netting or fabric, which are built across streams.By themselves they do little to stop oil, so oil-absorbing particulatematerial is placed on the upstream side to absorb oil as the waterpasses through. Although more effective than sock booms, this method islabor intensive. Fences must be built by hand and the oil absorbent mustbe placed and removed by hand. The absorbant material near the top islargely wasted, because it floats above the oil and is therefore unableto absorb it. It is difficult to place fenceposts in hard-bottomedstreams or concrete-filled drainage ditches, and difficult to affixfenceposts with the necessary permanence in areas with fast flowingwater or soft silt bottoms. In the event of a loss of fence integrity orunexpected water volume overtopping the fence, contaminatedoil-absorbing particulate can be scattered downstream, creating asecondary environmental hazard to complement the oil spill.

Mechanical skimmers of the type used to remove oils from industrialwastewater have also been employed, but they suffer from even moresevere deficiencies in real-world conditions than the above approaches.They do not handle waves or tides well, require a power supply tofunction, and have no barrier qualities at all, meaning they must becombined with hard booms or some other means of concentrating oil toallow it to be removed.

SUMMARY

The problems of the prior art are solved by a sorbent boom havingmultiple compartments of similar size in a single panel, permitting itto absorb oil more effectively than sock booms without halting the flowof water through the boom as hard booms do.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of the panel sorbent boomhaving 3 compartments.

FIG. 2 is a perspective view of the boom of FIG. 1 cut along line 2-2,showing the compartments in which fill material is placed.

FIG. 3 is a perspective view of a chain of booms weighted and floatingupright in a body of water.

FIG. 4 is an overhead view of one possible open-water application inwhich a chain of weighted booms is towed behind boats to gather upspilled oil, and a skimmer vessel follows the boom at its apex to pumpoil directly out of the water.

FIG. 5 is a perspective view of an alternative embodiment of the panelsorbent boom having two compartments.

FIG. 6 is a perspective view of the boom of FIG. 5 cut along line 6-6,showing the compartments in which fill material is placed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, the panel-type oil boom 10 is preferablycomposed of cover 12, which has front 12 a and back 12 b. The cover 12may be formed by one or more elongate tubes of material which permitboth water and oil to pass through easily. It may be formed of multipleseparate sheets of material as well. The material may be mesh or fabric,but is preferably non-biodegradable. Preferably, the boom 10 is aboutthree inches thick, about ten inches wide, and about six to ten feetlong. The front 12 a and back 12 b are joined to divide the cover 12into more than one, preferably two or three, compartments 18 a, 18 b,and 18 c that run longitudinally. This may be accomplished by attachingdividers 16 to the inner wall 14 of the cover 12 by attaching separatetubes of material to one another, or simply by attaching the front 12 ato the back 12 b along an elongate seam. The dividers 16 may be the samematerial making up the cover, or may be different. The attachment ofdividers 16 or of the front 12 a to the back 12 b may be accomplished byany means having suitable strength, such as sewing, gluing, or theapplication of heat to fuse the parts together. The dividers 16 andcover 12 combine to form a rectangular panel-like boom with a muchgreater surface area relative to its volume than conventional sockbooms.

Compartments 18 a, 18 b, and 18 c are filled with an oil absorbing fillmaterial. Preferably, this fill material absorbs oil but not water, sothat water may flow easily through the boom as a whole, but oil istrapped. The fill material should be lighter than water so that the boom10 can float while absorbing oil rather than sinking. Meltblownpolypropylene is preferred, and virgin rather than reclaimedpolypropylene is especially preferred. Other oil absorbing fillmaterials are also available and well known in the art. Each compartmentis closed in whatever manner will retain the fill material.

The boom 10 will preferably have some means of attaching it to otherbooms, to fixed structures, to boats, or to winches, reels, and othermeans of deployment. These attachment means 20 may be any well-knowndevice, such as grommets, fabric or wire loops, or clips. Theseattachment means 20 are already in use on conventional sock booms. Forillustrative purposes only, fabric loops are shown. Preferably, some ofthese attachment means 20 are located at or near the corners of the boom10. This permits the booms 10 to be joined in such a fashion as to keepthem substantially parallel with each other and prevent twisting.Additional attachment means 20 may be along the edges of the boom 10 topermit the booms 10 to overlap each other to maximize oil absorption. Inaddition, weights 22 may be attached to the attachment means 20 alongone edge so as to hold it upright in the water.

The booms 10 of the invention may be deployed in a number of ways. Forspills of limited scope in enclosed and relatively static bodies ofwater, they may simply be placed upon the water's surface and permittedto absorb any oil they encounter. This is an inexpensive means ofcleaning the water. Somewhat greater efficiency can be achieved byconnecting a plurality of booms 10 together and permitting the booms tofloat horizontally in an extended string. This method is simple andquick to set up and gives superior absorption compared to sock boomsbecause the flat design puts more oil-absorbing material near thesurface of the water, where it is needed. A flat-floating panel boom 10or string of panel booms 10 also deals with wave action better than sockbooms because waves that push the leading edge up tend to drive thetrailing edge downward, into the oil requiring absorption.

A preferred method for deploying booms 10, as shown in FIG. 3, is tolink them together into a chain and then apply weights 22 to theattachment means 20 all along one edge of the chain. By choosing theweights 22 appropriately, the chain may be caused to float vertically apredetermined distance out of the water. This distance may be adjustedto account for conditions, such as wave action, which may call for agreater distance to prevent overtopping, and depth of the oil slick,with deeper slicks requiring a lower floating boom 10 to prevent oilfrom slipping underneath. It is possible to manufacture booms 10 withweights 22 pre-attached to simplify deployment. This arrangement bothexposes a much greater surface area than sock booms, to maximizeabsorption, and also ensures that oil will not simply slip underneath.

The weighted chain of oil booms 10 may be positioned in any way whichmaximizes the chance of encountering oil. For instance, a set of booms10 may be deployed across a harbor mouth so that tidal action will causebilge oils to be collected before they escape the harbor. The chain maybe positioned to surround or “blockade” an environmentally sensitivesection of shoreline so that oil spills from the open sea will notaffect that area. It may be strung across a river or stream to captureoil from upstream and prevent it from doing further damage, and in thisapplication it is much more efficient than filter fences because all ofthe sorbent material is located near the surface of the water, where theoil is. A chain of booms 10 may be deployed in a circle around thesource of an oil spill or leak to contain it. It may be towed behind twoor more towing boats 24 in a “purse seine” action to surround andmitigate an otherwise uncontrolled spill, as depicted in FIG. 4. Theboats then steer to gather oil in a manner reminiscent of a purse seinegathering fish. A skimmer boat 26, which is well known in the art, maybe employed to pull oil 28 out of the water before it encounters thechain of booms 10. In this way more oil may be removed before the booms10 become saturated. These various applications may range from chains ofhundreds of booms 10 to surround leaking tanker ships to the placementof a single boom 10 across a drainage ditch at the site of an automobileaccident.

Because the booms 10 are not made of biodegradable materials, they maybe left in place indefinitely until saturated with oil. They may then beremoved and optionally replaced with fresh booms 10. This permitscleanup to occur naturally over an extended period of time with minimalhuman intervention. For instance, a tanker truck carrying some quantityof oil may crash on the roadways, leaking oil into drainage ditches orstorm drains which lead to local streams. While the bulk of the oil maybe cleaned up fairly promptly, some may cling to rocks or the roadwayand leach into the water only gradually. Booms 10 may be placed in thestream and left in place for extended periods of time to catch thisresidue until it has been reduced to an acceptably low level by thenatural water flow.

The terms and expressions that have been employed in the foregoingspecification are used therein as terms of description and not oflimitation, and there is no intention in the use of such terms andexpressions of excluding equivalents of the features shown and describedor portions thereof, it being recognized that the scope of the inventionis defined and limited only by the claims that follow.

1. An oil absorbing boom, comprising: a cover having a front and a back;a plurality of compartments formed within the cover by connecting saidfront and said back; and an oil absorbing fill material within saidcompartments.
 2. The boom of claim 1 wherein said oil absorbing fillmaterial is polypropylene.
 3. The boom of claim 2 where saidpolypropylene is virgin material.
 4. The boom of claim 1 wherein saidcompartments are elongate and arranged substantially parallel to eachother.
 5. The boom of claim 1 further comprising weights attached to theboom.
 6. The boom of claim 5 wherein said weights are so selected thatwhen placed in water, the boom floats at a predetermined depth.
 7. Theboom of claim 6 wherein said weights are so arranged that when placed inwater, the boom floats with said front and said back substantiallyperpendicular to the surface of the water.
 8. An oil absorbing boom,comprising: A plurality of elongate compartments, each having an length,formed of a flexible material, said compartments arranged substantiallyparallel to each other and joined along their lengths; and an oilabsorbing fill material within said compartments.
 9. The boom of claim 8wherein said oil absorbing fill material is polypropylene.
 10. The boomof claim 9 where said polypropylene is virgin material.
 11. The boom ofclaim 8 wherein said compartments all have a height and a width, whereinsaid compartments further have substantially the same width, and are soarranged that the boom has a width equal to the width of eachcompartment and an height equal to the sum of the compartments'respective heights.
 12. The boom of claim 11 further comprising weightsattached to one of the compartments.
 13. The boom of claim 12 whereinsaid weights are so selected that when placed in water, the boom floatsat a predetermined depth.
 14. The boom of claim 13 wherein said weightsare so arranged that when placed in water, the boom floats with thecompartments arranged substantially vertically relative to one another.15. A method of removing a contaminant from water, comprising the stepsof: providing a sorbent boom comprising a cover having a front and aback, a plurality of compartments formed within the cover by connectingsaid front and said back, and a contaminant-absorbing fill materialwithin said compartments; attaching weight said boom; and placing saidboom in water containing a contaminant.
 16. The method of claim 15wherein the boom is so weighted that when placed in water, the boomfloats with said compartments arranged substantially parallel to thesurface of the water and substantially vertically relative to oneanother.
 17. The method of claim 15 further comprising the step ofjoining a plurality of booms together to form a chain.
 18. The method ofclaim 15 wherein said water is in motion, and said boom is placed insaid water and affixed to an immobile object such that the water tendsto flow between said front and said back.
 19. The method of claim 15further comprising the step of attaching said boom to an object thatmoves through said water in such a fashion that the water tends to flowbetween said front and said back.